HOUSTON — Adam Rosales wanted to sleep, so he put his phone on vibrate.

Nice timing. Right after he did that Tuesday, A’s assistant general manager David Forst called, wanting to tell Rosales to pack, he was coming back to Oakland after a two-week hiatus in which Grant Green was given a chance to play some second base with the A’s.

Z-Z-Z-Z.

Forst called again a few minutes later. And a few minutes after that. He wound up having to call five times in 20 minutes before the phone’s vibrations were enough to awake the dozing Rosales.

“That’s the best kind of wakeup call,” Rosales said, grinning.

The A’s are hoping that Rosales will bring some kind of wakeup to the Oakland defense, which is floundering in the first few days after the All-Star break. The A’s have made six errors in the last two games and eight in the first five games since the resumption of play.

“He’s been here before, and he brings a lot of energy,” manager Bob Melvin said of Rosales. “And he’s a plus defender at every position. We’ve had some defensive issues and this is one guy who can clean it up.

“He brings passion.”

The plan will be to have Rosales start at shortstop against left-handed pitching with Jed Lowrie at second base. Against right-handers, it will be Lowrie at short and Eric Sogard at second base.

That’s as it was before Rosales was sent down. But there is likely to be a change from past usage for Rosales. If he comes in mid-game for Sogard, Rosales is likely to stay at second base. Melvin said he’s thinking it makes more sense to let Lowrie stay at one position for the entire game.

Left-handed starter Brett Anderson will get at least one more bullpen session this week as the A’s return home for a four-game series against the Angels. That’s after he threw about 40 pitches Wednesday morning in Houston and came out of it, in Melvin’s words, feeling nastier than when he threw on Monday.

The A’s want at least one more bullpen session for Anderson, probably on Friday, and they’ll have to decide at that point if he needs more work throwing off a pitcher’s mound or if it’s time for the opening day starter to face hitters for the first time since a sprained right ankle and a stress fracture in his right foot put him on the disabled list at the end of April.

He could be thrown into a simulated game against current A’s hitters or he might go directly out on an injury rehabilitation assignment. If it’s a simulated game or two, the next step beyond would be the injury rehab.

“There’s a natural progression,” Melvin said. “We’re looking at a rehab assignment if all goes well and if the next step is having him face hitters.”